A man suspected of mailing ricin to President Donald Trump and Defense Secretary James Mattis was taken into police custody in Logan, Utah, according to authorities.

“No wider threat to the public safety exists at this time,” said FBI Salt Lake City field office spokesman Doug Davis. “As it is a pending matter, that’s all we can say at this time.”

A spokesperson for the U.S. attorney for Utah identified the suspect as William Clyde Allen III.

Authorities were investigating two envelopes suspected of containing a suspected poison addressed to top military chiefs and a third with unknown contents sent to President Donald Trump.

In a statement Tuesday evening, the Secret Service confirmed that a suspicious envelope had been sent to the president on Monday but was not received at the White House, nor did it ever enter the building. The agency did not disclose any details about what was in the envelope or where it was received. The White House had no comment.

Authorities at a Pentagon mail screening facility were investigating two envelopes suspected of containing ricin, a poison made from castor beans. Those letters were addressed to Defense Secretary Jim Mattis, who is traveling in Europe this week, and the Navy’s top officer, Adm. John Richardson, a defense official said.

They were turned over to the FBI for further analysis. The official spoke on condition of anonymity because the official was not authorized to speak publicly ahead of the FBI’s release of its findings.

Neither envelope entered the Pentagon. The mail screening facility is on the Pentagon grounds but separate from the main building.

Pentagon spokesman Chris Sherwood said the envelopes had been found on Monday.

Another Pentagon spokesman, Col. Rob Manning, said all U.S. Postal Service mail received at the screening facility on Monday was under quarantine and “poses no threat to Pentagon personnel.”

Ricin is part of the waste “mash” produced when castor oil is made. According to the Centers for Disease Control and Prevention, if it is made into a partially purified material or refined, ricin can be used as a weapon capable of causing death under certain circumstances.